Electric motor controlled fluid valve

ABSTRACT

An electric motor controlled hydraulic or pneumatic valve including a valve housing having a main spool positioned to control the flow of fluid from a pressure port to a fluid circuit, the spool including a threaded bore at one end, a high speed low torque reversible electric motor mounted on said housing and being connected to the spool by a threaded rod to provide high torque output to the spool and an electric control circuit including a bridge circuit having a manually controlled variable resistance, a feed back variable resistance mechanically connected to the spool, and a pair of solid state switches or relay circuits connected across the bridge circuit to provide an electric signal to the electric motor in response to movement of the manually controlled variable resistance.

3,756Jll2 Sept. 4, W73

ELECTRIC MOTOR CONTROLLED FLUID VALVE Inventor: Dale A. Knutson,Oconomowoc,

Wis.

Assignee: Applied Power Inc., Milwaukee, Wis.

Filed: May 30, 1972 Appl. No.: 257,968

U.S. Cl. 137/625.64, 251/133 Int. Cl. Fl6k 11/00 Field of Searchl37/625.64, 625.65, l37/625.25, 625.29, 625.34; 251/133, 134, 135

References Cited UNlTED STATES PATENTS l2/l969 Fleckcnstein et all37/625.64 X

Primary ExaminerHenry T. Klinksiek Assistant ExaminerRobert J MillerAttorney-James E. Nilles [57] ABSTRACT An electric motor controlledhydraulic or pneumatic valve including a valve housing having a mainspool positioned to control the flow of fluid from a pressure port to afluid circuit, the spool including a threaded bore at one end, a highspeed low torque reversible electric motor mounted on said housing andbeing connected to the spool by a threaded'rod to provide high torqueoutput to the spool and an electric control circuit including a bridgecircuit having a manually controlled variable resistance, a feed backvariable resistance mechanically connected to the spool, and a pair ofsolid state switches or relay circuits connected across the bridgecircuit to provide an electric signal to the electric motor in responseto movement of the manually controlled variable resistance.

15 Claims, 6 Drawing Figures 'PATENIED SEP 4 I915.

SHEEI 2 0f 3 PAIENTEUSEP 4 ms SHEET 3 0F 3 ELECTRIC MOTOR CONTROLLEDFLUID VALVE SUMMARY OF THE INVENTION The fluid valve of the presentinvention provides for automatic motor control of a hydraulic orpneumatic. valve by a single stage drive. The movement of the valvespool is achieved by a threaded connection between an electric motor anda threaded bore in the valve spool. With this arrangement, it ispossible to use a high-speed, low torque electric motor and obtain hightorque output for controlling a high flow valve. The valve may beprovided with a manual override. Accuracy in metering the flow of fluidis achieved by providing a movement to the valve spool which correspondsto the movement of the controller. This is achieved by usinga feed backloop which includes a variable resist'ance that is connected to thevalve spool. The electric motor will stop when the valve spool has moveda distance corresponding to the direction and distance of movement ofthe controller.

DRAWING FIG. 1 is a cross sectional view of thevalve of this inventionshowing a dc wiring circuit;

FIG. 2 is an enlarged view of a portion of the valve showing the driveconnection;

FIG. 3 is a schematic view of the control circuit;

FIG. 4 is a view of a modified type valve having a manual override;

FIG. 5 is a view of another modified type valve having a manualoverride; and

FIG. 6 is a schematic wiring diagram for the valve showing an ac powercircuit.

DESCRIPTION OF THE INVENTION The electric motor controller valve 10 ofthe present invention includes a valve 12 and a reversible electricmotor 14. The electric motor 14 is controlled by means of an electriccircuit 16 having solid stateor solenoid actuated switches, 18 and 20for controlling the direction of rotation of the motor 14. A low powercontrol circuit 22 which includes a manual input controller 24 having avariable resistance 25 and a feed back variable resistance 26 to controlthe solenoid switches 18 and 20. Movement of the controller 24 in eitherdirection will produce a corresponding energization of the motor 14 toopen the valve 12. The amount of movement of the controller 24 producesa corresponding amount of movement of the valve spool 42 through thefeed back signal from the variable resistance 26. i The Fluid ValveThevalve 12 can .be any conventional type fluid control valve eitherhydraulic or pneumatic and as seen in FIG. 1 generally includes a valvehousing 28 having a cylindrical bore 30. A pressure port 32 is centrallylocated in the valve housing 28 and a number of relief ports 34 areconnected to a tank 35 through a passage 36. A pair of fluid circuitpassages 38 and are provided in the housing 28 and are connected to afluid circuit.

Flow of fluid from the pressure port 32 to the fluid circuit passages 38and 40 is controlled by a spool 42 positioned in the cylindrical bore30. The spool 42 includes a first or central land 44 which is positionedto control the pressure port 32, second and third lands 46 and 48 whichare positioned to control flow to the relief ports 34 and a threadedbore at one end. Movement of the spool 42 to the right will open thepressure port 32 allowing fluid to flow through the bore 30 to the fluidcircuit passage 38. Fluid returned through passage 40 will flow throughthe relief port 34 to tank. Movement of the spool 42 to the left willopen the pressure port 32 allowing fluid to flow through the bore 30 tothe fluid passage 40. Fluid returned through passage 38 will flowthrough the relief port 34 to tank 35. Other conventional types of valvespool configurations and porting may also be employed with this means ofcontrol.

The Electric Motor The reversible electric motor 14 is mounted on an endblock 50 which is positioned in a counterbore 52 at the end of thecylindrical bore 30 of the valve housing 28 and has a central opening47. The output shaft 54 of the motor 14 is connected to. the spool 42 bymeans of a thrust assembly 56.

In this regard, the thrust assembly 56 is positioned within a recess 58provided on the inner side of the block 50. The assembly 56 includes adrive shaft or rod 60 which extends through the opening 47. Anexternally threaded section 62 is provided at one end and an internallythreaded bore 64 is provided at the other end. The rod 60 is threadedlyconnected to the drive shaft 54 of the electric motor 14 and is pinnedor locked to the drive shaft by a pin 66. The threaded section 62 of therod 60 is threadedly received in the threaded bore 45 provided on theend of the spool 42. The rod 60 is sealed in the opening 47 by means ofan O-ring seal 49.

Fluid pressure built up in the bore 45 is relieved by means of a passage61 in the rod 60and a cross bore 63 at the inner end of the passage 61.Axial forces exerted on the rod 60 are relieved by thrust bearings 68and 70 provided on each side of a radial flange 72 on the rod 60.

On rotation of the rod 60 by the motor 14 the spool 42 will move axiallyin either direction in the bore 30 depending on the direction ofrotation of the rod 64) due to the threaded connection between thethreaded section 62 and the threaded bore 45. Means are provided forpreventing rotation of the spool 42 due to the rotary motion of thedrive shaft or rod 66. Such means is in the form of a ball 51 providedin a port 53 in the valve housing 28 and a groove 55 in the spool 42.The ball 51 is retained in the port 53 by means of a plug 57 threadedlyreceived in the port 53. The plug 57 is sealed in the port 53 by meansof an O-ring seal 59.

Means are provided for producing an electric signal in response tomovement of said valve spool 42 in the form of variable resistance 26.The axial movement of the spool 42 is transmitted to the variableresistance 26 by means of a rod 43. The rod 43 is connected to the spool42 and to the variable resistance 26 through an opening 35 in the end ofbore 36. The rod 43 is sealed in the opening 35 by an O-ring seal 37.

The valve contemplated in the present invention is capable of relativelyhigh flow rates (e.g., 30 to gallons per minute). In order to achievemaximum flow, the spool 42 must be moved approximately plus or minus0.250 inch or more in either direction. In a valve of this type, theresponse characteristic required is generally approximately 2.5 cyclesper second.

The motor required to provide the above requirements for the valve is anAC or DC reversible motor having a continuous duty cycle at rated load.This type of motor is normally characterized as being a high speed lowtorque motor.

In order to obtain the desired response characteristic of 2.5 cycles persecond the pitch of the thread on the threaded section 62 of rod 60 isdetermined by the rpm of the motor and the maximum stoke of the spool42. The mechanical advantage of the thread which enages rod 60 withspool 42 provides a relatively high driving force to move the spool 42against frictional and flow forces.

The Electric Circuit The reversible DC motor 14 is controlled by meansof the electric circuit 16 which includes an electric line 90 connectedto a DC power source 92 and to the solid state or solenoid switches 18and 20 by lines 94 and 96. The line 96 is connected to the reversiblemotor 14 by lines 98. The line 94 is connected to the motor 14 by line100. The line 98 is connected to ground 91 through switch 18 by line102. The line 100 is connected to ground 91 through switch 20 by line104.

The valve 12 is actuated by closing switch 20 to energize the motor 14through lines 90, 96 and 98, 100 and 104 or by closing switch 18 toenergize motor 14 through lines 90, 94, 100, 98 and 102. The directionof rotation of the motor 14 can be set to move the valve 42 in the samedirection as the motion of the controler 24.

If an AC motor 200 is used in place of a DC motor, the electric circuit202 should be as shown in FIG. 6. The circuit 202 is connected to an ACpower source by lines 204 and 206. The line 204 is connected to solenoidswitch 18 by line 205, to solenoid switch 20 by line 207 and to themotor 200 by line 208. The line 206 is connected to the solenoid switch18 by lines 209, to the solenoid switch 20 by line 210 and to the ACmotor 200 by line 211. The AC motor is connected to the so- I lenoidswitch 18 by lines 212 and 213 and to the solenoid switch 20 by lines214 and 215. The solid state or solenoid switches 18 and 20 arecontrolled by the DC control circuit as described hereinafter. Closingof switch 18 or switch 20 will complete the corresponding circuit to theact motor producing opposing directions of rotation with a correspondingmovement of the valve spool. The Control Circuit The motor circuit 16 iscontrolled by means of the low power control circuit 22 which includesthe manual input controller 24 and the feedback resistance 26. Referringto FIG. 1, it will be noted that the control circuit is in the form of abridge circuit having a'first leg or line which includes the controllerresistance 25, a sec- 0nd leg or line 112 which includes a fixedresistance 114, a third leg 118 which includes a fixed resistance 120, afourth leg 116 which includes the variable resistance 26.

Referring to FIG. 3, a schematic wiring diagram of the bridge circuit isshown with the first and third lines 110 and 1 16 connected to the DCpower source 92 and the second and third lines 112 and 118 connected tothe ground 91. The solid state switch or coil 122 for the solenoidswitch 118 is connected across the bridge circuit by line 124 whichincludes a diode 126. The solid state switch or coil 128 for thesolenoid 20 is connected across the bridge circuit by a line 130 whichincludes a diode 132. As is generally understood in a bridge circuit,the fixed resistance R1 and R2 are balanced and movement of the manualcontroller 24 will produce an unbalance in the system causing a currentto flow through one or the other of the lines 124 or 130, depending onthe diodes 126 and 132.

Assuming current flow through 124, the solenoid 18 will be closed,energizing the motor 14. If the motor 14 produces a movement of thespool 42 to the left, it will connect passage 32 with circuit passage 40and passage 38 to the return passage 34. A corresponding movement willalso occur in the variable resistance 26, changing the resistance 26until it is again balanced or equal to the resistance 25. Once thebridge circuit is balanced, the current will stop in line 124,deenergizing the solenoid l8 and opening the circuit to the motor 14.

Assuming current flow through the line 130, the solenoid switch 20 willbe closed, energizing the motor 14 but producing opposite rotation ofthe drive shaft 54. If the motor produces a movement of the spool 42 tothe right, it will connect passage 32 with circuit passage 38 andpassage 40 with return passage 34. A corresponding movement will alsooccur in the variable resistance 26 but in the opposite direction,changing the resistance 26 until it is again balanced or equal to theresistance 24. It should be noted that the position of the controller 24always determines the position of the valve spool since the resistance26 must move to the same position before the motor stops.

Manual Override (FIG. 4)

A modified valve is shown having a manual override assembly 142. In thisregard, the spool 42 for the valve is separated into a drive section 420and a control section 42b. The drive section 42a includes a threadedbore 45 which is threadedly connected to the drive shaft 60 as describedabove. Rotation of drive section 42a is prevented by means of a ball 51positioned to engage a groove 55 provided in the drive section 42a.

The control section 42b is centered or retained in the null position bymeans of springs 144 and 146 of substantially equal spring rates. Thespring 144 is positioned between the drive section 42a and controlsection 42b/The spring 146 is positioned between the other end of thecontrol section 42b and the end of the passage 30 in the housing 28.

The control section 42b is moved manually in the passage 30 by means ofthe manual override assembly 142. In this regard, the control section42b includes a fourth land 148 having an outer groove 150. A handle 152is mounted for pivotal movement on a shaft 154 which includes a lever155 at its inner end having a ball 156 positioned in the groove 150.Movement of the handle 152 either clockwise or counterclockwise willproduce a corresponding movement of the control section 42b against thebias of one or the other of the springs 144 and 146. On release of thehandle, the compressed spring 144 or 146 will return the spool controlsection 42b to the null position. It should be apparent that normaloperation of the electric motor will move the drive section 42a eithertoward or away from the control section with the spring 144 or 146moving the control section 42b in the same direction as the drivesection 420.

Manual Override (FIG. 5)

In another form of override valve 240, a manual override assembly 242 isshown having means for preventing movement of the handle 250 duringnormal electric motor operation of the valve. In this embodiment, thevalve spool includes a drive section 242a, a

control section 2421: and an override section 242c. The control section242b is centered or biased to a null position by means of thecompression springs 244 and 246, respectively.

In this regard, the spring 244 is positioned between the drive section242a and the control section 242b. The spring 246 is positioned betweenthe control section 242b and the override section 242c. A third spring248 can be positioned between the override section 2420 and the end ofthe passage 30. During normal electric motor operation, the axialmovement of the drive section to the right or left will either compressor expand springs 244 and 246 producing a corresponding movement in thecontrol section 242b.

Manual override of the control section 24212 is accomplished by means ofthe override assembly 242c. In this regard, the override section 242c isprovided with an annular groove 252 and a central passage 254. Thehandle 250 is connected to a pivot shaft 256 which includes a lever arm258 having a ball 260 at its outer end positioned in groove 252. Thehandle 250 is normally locked by a pin and latch assembly 261 in a fixedposition so that it will also hold the override section 242c in a fixedposition. On movement of the lever 250 either clockwise orcounterclockwise a corresponding movement will be transferred to theoverride section 242c producing a corresponding change in the positionof the control section 242k. The feedback resistance 26 is connected tothe control section 24% by means of a rod 260 through the passage 254 inthe override sec-- tion 242c to provide a direct relation between themovement of the control section'242b and the feedback resistance 26.

'I claim:

ll. An electric motor controlled hydraulic or pneumatic valvecomprising:

a valve housing having a cylindrical bore,

a valve spool mounted for axial movement in said bore for controllingthe flow of fluid through said valve housing, said spool having athreaded bore in one end, a reversible high speed low torque electricmotor mounted on one end of said housing and having an output shaftextending into said cylindrical bore,

means for threadedly connecting the output shaft of said motor to saidthreaded bore,

an electric power circuit operatively connected to said motor,

and a low power electric control circuit connected to said electricpower circuit to control said electric circuit, said control circuitincluding manual input means and an electric signal means connected torespond to the movement of said valve spool to de-energize said motorupon movement of said valve spool a distance corresponding to thedistance of movement of said input means.

2. A valve according to claim 1 wherein said power circuit includes apair of solid state or solenoid switches and said control circuitincludes a bridge circuit having a pair of relay circuits connected toactuate one or the other of said solid state or solenoid switches tothereby control the direction of rotation of said motor.

3. A valve according to claim 1 wherein said manual input means includesa first variable resistance and said electric signal means includes asecond variable resistance,

a bridge circuit having a first fixed resistance connected in serieswith said first variable resistance and a second fixed resistanceconnected in series with said second variable resistance and a pair ofrelay circuits connected across said bridge circuit.

4. The valve according to claim 1 including means for manuallyoverriding said drive motor.

5. The valve according to claim 4 wherein said valve spool includes adrive section and a control section, means for biasing said controlsection to a null position and said manual override means includes ahandle operatively connected to move said control section independent ofsaid drive section.

6. The valve according to claim 4 wherein said valve spool includes adrive section, a control section and an override section, said manualoverride means comprising a handle operatively connected to saidoverride section.

7. An electric motor controlled fluid valve comprising:

a valve housing having a cylindrical bore,

a valve spool mounted for axial movement in said bore for controllingthe flow of fluid through said housing, said spool having a threadedbore at one end,

a reversible high speed low torque electric motor mounted on one end ofsaid housing and having an output shaft extending into said cylindricalbore,

means for threadedly connecting the output shaft of said motor to saidthreaded bore, and

means for selectively energizing said motor whereby the rotary motion ofsaid motor produces axial movement of said valve spool.

8. The valve according to claim 7 including means for manually movingsaid valve spool. I

9. The valve according to claim 7 wherein said valve spool includes adrive section and a control section,

and a manual override means including a lever operatively connected tosaid control section.

10. The valve according to claim 7 wherein said means for energizingsaid motor includes an electric power circuit and an electric controlcircuit connected to control said power circuit, said control circuithaving a manual input' means and an electric signal feed back meansconnected to respond to the movement of said valve spool to de-energizesaid motor upon displacement of said spool a distance corresponding tothe distance of movement of said input means.

111. The valve according to claim 7 wherein said valve spool includes adrive section, a control section and an override section and means forbiasing said control section to a null position in said bore and meansoperatively connected to said override section for moving said controlsection independently of said drive section.

12. An electric motor controlled fluid valve comprising: r

a valve housing having a central flow passage connected to an inletport, a tank port and a pair of fluid flow ports,

a valve spool mounted in said central flow passage to control the flowof fluid between said inlet port and one of said fluid flow ports andbetween the other of saidfluid flow ports and said tank port, said valvespool having a threaded bore at one end,

means for preventing rotary motion of said valve spool on axial movementin said passage,

a reversible high speed low torque electric motor mounted on one end ofsaid valve housing and having a drive shaft,

means threadedly connecting said drive shaft to one said threaded borein said valve spool,

an electric power circuit connected to said motor,

and an electric control circuit connected to said power circuit, saidcontrol circuit including a manually controlled variable resistancemechanically connected to said valve spool.

13. The valve according to claim 12 wherein said control circuitcomprises a bridge circuit having a pair of relay switches connected tocontrol said power circuit, said manually controlled variable resistanceand said feedback variable resistance being connected in said bridgecircuit.

14. A valve according to claim 12 wherein said valve spool includes adrive section and a control section, means for biasing said controlsection to a null position in said passage and manual override means formoving said control section independently of said drive section.

15. A valve according to claim 12 wherein said valve spool includes adrive section, a control section and an override section, means forbiasing said control section to a null position in said passage andmeans for manually moving said override section to move said controlsection independently of said drive section.

1. An electric motor controlled hydraulic or pneumatic valve comprising:a valve housing having a cylindrical bore, a valve spool mounted foraxial movement in said bore for controlling the flow of fluid throughsaid valve housing, said spool having a threaded bore in one end, areversible high speed low torque electric motor mounted on one end ofsaid housing and having an output shaft extending into said cylindricalbore, means for threadedly connecting the output shaft of said motor tosaid threaded bore, an electric power circuit operatively connected tosaid motor, and a low power electric control circuit connected to saidelectric power circuit to control said electric circuit, said controlcircuit including manual input means and an electric signal meansconnected to respond to the movement of said valve spool to de-energizesaid motor upon movement of said valve spool a distance corresponding tothe distance of movement of said input means.
 2. A valve according toclaim 1 wherein said power circuit includes a pair of solid state orsolenoid switches and said control circuit includes a bridge circuithaving a pair of relay circuits connected to actuate one or the other ofsaid solid state or solenoid switches to thereby control the directionof rotation of said motor.
 3. A valve according to claim 1 wherein saidmanual input means includes a first variable resistance and saidelectric signal means includes a second variable resistance, a bridgecircuit having a first fixed resistance connected in series with saidfirst variable resistance and a second fixed resistance connected inseries with said second variable resistance and a pair of relay circuitsconnected across said bridge circuit.
 4. The valve according to claim 1including means for manually overriding said drive motor.
 5. The valveaccording to claim 4 wherein said valve spool includes a drive sectionand a control section, means for biasing said control section to a nullposition and said manual override means includes a handle operativelyconnected to move said control section independent of said drivesection.
 6. The valve according to claim 4 wherein said valve spoolincludes a drive section, a control section and an override section,said manual override means comprising a handle operatively connected tosaid override section.
 7. An electric motor controlled fluid valvecomprising: a valve housing having a cylindrical bore, a valve spoolmounted for axial movement in said bore for controlling the flow offluid through said housing, said spool having a threaded bore at oneend, a reversible high speed low torque electric motor mounted on oneend of said housing and having an output shaft extending into saidcylindrical bore, means for threadedly connecting the output shaft ofsaid motor to said threaded bore, and means for selectively energizingsaid motor whereby the rotary motion of said motor produces axialmovement of said valve spool.
 8. The valve according to claim 7including means for manually moving said valve spool.
 9. The valveaccording to claim 7 wherein said valve spool includes a drive sectionand a control section, and a manual override means including a leveroperatively connected to said control section.
 10. The valve accordingto claim 7 wherein said means for energizing said motor includes anelectric poweR circuit and an electric control circuit connected tocontrol said power circuit, said control circuit having a manual inputmeans and an electric signal feed back means connected to respond to themovement of said valve spool to de-energize said motor upon displacementof said spool a distance corresponding to the distance of movement ofsaid input means.
 11. The valve according to claim 7 wherein said valvespool includes a drive section, a control section and an overridesection and means for biasing said control section to a null position insaid bore and means operatively connected to said override section formoving said control section independently of said drive section.
 12. Anelectric motor controlled fluid valve comprising: a valve housing havinga central flow passage connected to an inlet port, a tank port and apair of fluid flow ports, a valve spool mounted in said central flowpassage to control the flow of fluid between said inlet port and one ofsaid fluid flow ports and between the other of said fluid flow ports andsaid tank port, said valve spool having a threaded bore at one end,means for preventing rotary motion of said valve spool on axial movementin said passage, a reversible high speed low torque electric motormounted on one end of said valve housing and having a drive shaft, meansthreadedly connecting said drive shaft to one said threaded bore in saidvalve spool, an electric power circuit connected to said motor, and anelectric control circuit connected to said power circuit, said controlcircuit including a manually controlled variable resistance mechanicallyconnected to said valve spool.
 13. The valve according to claim 12wherein said control circuit comprises a bridge circuit having a pair ofrelay switches connected to control said power circuit, said manuallycontrolled variable resistance and said feed back variable resistancebeing connected in said bridge circuit.
 14. A valve according to claim12 wherein said valve spool includes a drive section and a controlsection, means for biasing said control section to a null position insaid passage and manual override means for moving said control sectionindependently of said drive section.
 15. A valve according to claim 12wherein said valve spool includes a drive section, a control section andan override section, means for biasing said control section to a nullposition in said passage and means for manually moving said overridesection to move said control section independently of said drivesection.